: The current method of making a histological diagnosis is excisional biopsy. A major limitation of biopsy is sampling error. Unless a discrete mass is present, the site of biopsy is arbitrarily chosen so that the abnormal pathology may not be present in the sample. To circumvent this problem, the PI proposes to develop an acoustic microscope mounted at the tip of an endoscope, cardiac catheter or laparoscope, which will permit in situ imaging of cells. This will permit making a histological diagnosis without biopsy or alternatively targeted biopsy is feasible. Potential clinical applications of acoustic microscopy include in situ imaging of premalignant conditions such as Barrett's esophagus, detection of early malignancy in the esophagus and other parts of the gastrointestinal tract and visualization of myocardial pathology. Preliminary experiments indicate a 200 MHz transducer which provides an optimal trade-off between the resolution required for imaging cells and the depth of penetration of ultrasound. The PI proposes to construct a 200 MHz scanning acoustic microscope mounted at the tip of an endoscope. The transducer will be made of zinc oxide that will be deposited by reactive sputtering. An ultrasonic motor will be used to scan the transducer to generate a B-scan image. PROPOSED COMMERCIAL APPLICATION: The proposed commercial application of the endoscope based acoustic microscope is screening for early malignancy in conditions such as Barrett's esophagus.